JPH11245635A - Safety pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the weight of a tire while keeping normal running performance at a high level with inner pressure filled up and to enhance runflat running performance. SOLUTION: This tire has side walls, a carcass layer, a belt, and a tread part 22 disposed in order for reinforcing, and the tire is provided with a reinforcing rubber layer 24 in a crescent moon shape in cross section for the inner circumferential surface of the carcass layer 18 (18A and 18B) of each side wall. In this case, a rubber-covered cord side reinforcing layer 26 (for example, a cord angle with respect to the radial direction is 0 to 30 deg.) employing aramid fiber cords, is disposed to the outer circumferential side of the carcass layer for the side walls, and aliphatic polyamid fibers are used as the carcass cord of the carcass layer 18 (18A and 18B).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic safety tire which reinforces a tire side portion and enables good run flat running.

[0002]

2. Description of the Related Art A pneumatic tire is capable of run-flat running (that is, a punctured tire has a tire internal pressure of 0 kg / c).
even if the m ^2, a certain distance a vehicle can travel with peace of mind) tire (referred pneumatic safety tire) is the portion of the rim in an air chamber of the tire, mounted metal, synthetic resin annular core There are known a core type and a side reinforcement type in which a relatively hard rubber layer having a crescent cross section is arranged on the inner surface of the carcass from the bead portion of the tire sidewall to the shoulder region and reinforced. Of these two types, the core type has a high load-bearing capacity in run-flat driving, so it is intended for use in luggage-carrying vehicles and military vehicles where ride comfort is not an issue. However, they are small, and have been evaluated as appropriate for passenger cars that emphasize riding comfort.

[0003] Currently, pneumatic safety tires that are being developed are often side reinforced types.
On the inner surface of the carcass layer on the side wall, a relatively hard reinforcing rubber layer with a crescent cross section, one end of which overlaps with the belt layer across the carcass, and the other end overlaps with the rubber filler. Placement has been strengthened. If the tire punctures during running and the air escapes, the load is supported by the inherent rigidity of the sidewall reinforced with the reinforcing rubber layer, and although the speed must be slightly reduced, the run-flat running for a predetermined distance It can be carried out.

As described above, various side-reinforcement type safety tires have been conventionally proposed. However, most of them are flat high-performance tires, that is, low in flatness ratio mounted on a sports car (specifically, 60 tires). %), For vehicles with relatively low axle loads. Even with these flat high-performance tires, run-flat running durability is still not sufficiently satisfactory. In addition,
The flatness is expressed as {(tire height) / (tire width)} × 100 when mounted on the rim, and the flat tire refers to a tire having a flatness of less than 60%.

On the other hand, with the recent increase in demands on safety, safety tires are also required for general-purpose passenger car tires having an aspect ratio of 60% or more.

[0006] In the case of tires for general-purpose passenger cars, even if the load burden is relatively small, when the size of the passenger car is large, the load per tire is about 500 kgf. With such tires, when running in a punctured state, the deformation of the sidewalls increases, and the sidewalls are completely buckled by several times the dynamic load received during running, and the vehicle travels while repeating this.

In recent years, cords made of polyester fiber having high dimensional stability and high strength have been widely used as cords for reinforcing tires. However, when the sidewalls are greatly deformed as described above, the internal temperature becomes extremely high due to self-heating. As a result, peeling due to heat occurs at the bonding interface between the polyester fiber cord and the rubber, which causes a decrease in durability during run flat running.

Further, in the prior art, a reinforcing rubber layer having a crescent cross section is disposed mainly inside the carcass layer of the side wall portion to maintain the strength. However, actually, the rigidity of the side wall portion is further increased. In addition, the carcass layer is
It is necessary to have three or four layers, which is larger than the number of layers, and there is a problem in normal running that the weight increases, and further, the rolling resistance and the steering stability deteriorate.

On the other hand, in recent years, as the fuel economy of vehicles has been reduced, the weight of tires has been strongly required to be reduced. In order to reduce the weight of tires, the thickness of tire sidewalls has been increasingly reduced. In addition to maintaining the run-flat running performance of 0 kg / cm ^2, it is naturally required to improve the performance in normal running when filling the tire with the internal pressure, that is, to improve the running performance by reducing the tire weight.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to realize a lighter weight while maintaining a high level of normal running performance when filling with an internal pressure, and to achieve a run flat compared to a safety tire having a conventional reinforcing rubber layer. It is an object of the present invention to provide a pneumatic safety tire having significantly improved running performance.

[0011]

In order to solve the above-mentioned problems, the present inventors have made intensive studies on the relationship between the tire sidewall portion and the run-flat running performance of the tire. The inventors have found that the object can be achieved by the following means such as disposing the layer on the outer peripheral portion of the carcass layer near the reinforcing rubber layer having a crescent cross section on the side wall, and have completed the present invention.

That is, (1) the pneumatic safety tire of the present invention is formed such that a sidewall having a bead ring embedded at a tip portion thereof extends radially inward from both ends of the cylindrical crown portion, and the crown portion extends from one of these sidewalls. Between the carcass layer and the other side wall of the carcass layer, which is made up of at least one fiber cord radial ply, and whose both ends are wound up around the bead ring in the axial direction and fixed. A plurality of non-extensible belt layers, and a tread portion are sequentially arranged and reinforced respectively, and a pneumatic safety tire having a crescent-shaped reinforcing rubber layer in cross section on the inner peripheral surface of the carcass layer of the sidewall. A reinforcing cord made of an aliphatic polyamide-based fiber is used for the carcass layer; Aramid fibers, characterized in that the at least one layer disposed rubberized cord reinforcing layer made of a code rubberized.

Here, as the aliphatic polyamide fiber, a 46 nylon fiber is a preferred embodiment.

When the air from the pneumatic safety tire is deflated, the sidewall is bent and the tire is broken due to rubbing or the like, and the vehicle cannot run. Therefore, in the present invention, on the inner peripheral surface of the carcass layer, in a pneumatic tire having a crescent-shaped reinforcing rubber layer in cross section, adjacent to the crescent-shaped reinforcing rubber layer, preferably adjacent to the carcass layer, A rubber-coated cord reinforcing layer using high-elasticity, high-modulus aramid fiber is arranged, and high adhesiveness to rubber can be maintained even at high temperatures by using an aliphatic polyamide-based fiber for the carcass cord. Thus, separation of the interface between the cord and the rubber in the carcass layer could be prevented, and a pneumatic safety tire having excellent run-flat running durability was obtained.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, when the sidewall of the carcass layer is bent when the air from the tire is released, a tensile stress acts on the vicinity of the outer periphery of the carcass layer. Therefore, the tire is disposed adjacent to the crescent-shaped reinforcing rubber layer. As the rubber-coated cord reinforcing layer to be used, a rubber-coated cord using a high modulus aramid fiber is used. The aramid (aromatic polyamide) fiber used here is a fiber having a high modulus, a high tensile modulus, and an ultra-high modulus that is excellent in heat resistance.

The reinforcing rubber layer having a crescent cross section on the inner peripheral surface of the carcass layer used in the present invention suppresses the deflection of the sidewall when the air of the pneumatic safety tire escapes.
It is necessary to have a function (for example, high hardness) of suppressing the compression deformation inside the sidewall. Examples of the rubber component of the reinforcing rubber layer used to exhibit this function include natural rubber (NR), butadiene rubber (BR), and styrene-
Examples thereof include butadiene rubber (SBR) and isoprene rubber (IR). Among them, natural rubber and butadiene rubber are preferable from the viewpoint of the effect.

In the pneumatic safety tire according to the present invention, the rubber-coated cord reinforcing layer is disposed adjacent to a carcass layer near the reinforcing rubber layer having a crescent cross-sectional shape.
The load in the vicinity of the outer periphery of the carcass is shared and supported, but as in the present invention, the rubber-coated cord reinforcing layer may be disposed so as to have a contact surface with the carcass layer with respect to the reinforcing rubber layer having a crescent cross section. It is preferable from the viewpoint of suppressing the deformation of the wall. Further, a plurality of rubber-coated cord reinforcing layers may be provided.

In the pneumatic safety tire of the present invention, the angle of the aramid fiber cord of the rubber-coated cord reinforcing layer for reinforcing the sidewall is 0 to 30 with respect to the radial direction.
° is preferred. If the angle exceeds 30 °, the effect of suppressing the deflection of the side wall is undesirably reduced.

In the pneumatic safety tire of the present invention, it is preferable to use a reinforcing cord made of an aliphatic polyamide-based fiber for the carcass layer. Aliphatic polyamide fiber cord has high strength and excellent fatigue resistance, and furthermore, if the deflection of the sidewall portion is small as in the tire configuration of the present invention, there is no problem in creep property and heat resistance is high. In the present invention, it is suitable as a tire reinforcing cord in the carcass layer. Examples of the aliphatic polyamide fibers that can be used include 46 nylon and 66 nylon. Among them, 46 nylon is preferable from the viewpoint of strength and fatigue resistance.

In the pneumatic safety tire according to the present invention, it is preferable that at least one belt reinforcing layer is disposed on the entire tread portion on the outer peripheral side of the belt layer from the viewpoint of tire durability. This belt reinforcing layer is formed by being spirally and endlessly wound so as to be substantially parallel to the tire circumferential direction.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
A description will be given using examples and comparative examples.

FIG. 1 shows an example of a schematic sectional view of this pneumatic safety tire. In the pneumatic safety tire 10 of the present invention, a sidewall 16 in which a bead filler 14 and a bead ring 12 are buried is connected to a tip portion from both ends of a cylindrical crown portion toward a radially inner side.
Carcass layers 18a and 18b are formed of at least one fiber cord radial ply extending from one side to the other side wall through the crown portion, and both ends of which are wound up around the bead ring 12 in the axial direction and fixed. Among them, the end of the outer ply 18a is fixed near the bead filler 14, and the end of the inner ply 18b is fixed so as to overlap with the end of the belt layer 20. Further, a plurality of non-extensible belt layers 20 are provided on the outer periphery of the crown portions of the carcass layers 18a and 18b, and at least one belt reinforcing layer (cap layer layer), not shown, is provided on the outer peripheral side of the belt layer as necessary. The reinforcing rubber layer 24 (for example, a crescent-shaped section) that supports the load on the inner peripheral surface of the carcass layer 18 of the sidewalls 16 while sequentially reinforcing the tread portion and the tread portion 22 by sequentially disposing the tread portions 22 (for example, An aramid fiber cord (thickness of 1 mm) is provided on the outer peripheral side of the carcass layer 18 of the side wall 16 near the reinforcing rubber layer 24 having a maximum thickness of 7 mm and a hardness of 80 ° and having a crescent-shaped cross section.
670 dTex × 2) Rubber-coated cord reinforcing layer 2
6 (for example, the cord angle is 0 to 30 ° with respect to the radial direction)
Are arranged.

Various evaluation methods used in Examples and Comparative Examples are as follows. -Hardness is represented by JIS A and JIS K6301-1.
995.

The run flat durability is set to an internal pressure of 3.0 (Kgf
/ cm ² ), leave it at room temperature of 38 (° C.) for 24 hours, remove the valve core, reduce the internal pressure to 0 (Kgf / cm ² ), load 510 (Kg), speed 80 (Km / hr) A drum running test was conducted under the conditions of room temperature and 38 (° C.). At this time, the run flat durability was calculated from the running distance until the occurrence of the failure, and was represented by an index with the control (Comparative Example 1) being 100. The larger the value, the better the run flat durability. (Examples 1 and 2) (Comparative Examples 1 to 4) The size of the pneumatic safety tire used is 225/55.
R16 has a tubeless structure. As a carcass (body ply) layer, a two-ply ply cord shown in Table 2 below is used.
A crescent-shaped reinforcing rubber layer, a rubber having a hardness of 80 ° after vulcanization and a maximum thickness of 7 mm with a composition according to Table 1 and a belt layer having a 1 × 5 structure and a wire diameter of 0 mm was used. .25 mm steel cords were driven 40 threads / 5 cm, and the steel cord angle was 2 with respect to the tire circumferential direction.
A steel belt layer of 0 ° was used in a separated structure, and 2100 dTex 2 was used as a belt reinforcing layer.
The number of the twisted nylon cord is 40 / 5cm,
The nylon cord was used in a cap layer structure in which the angle was 0 ° with respect to the tire circumferential direction.

Further, according to Table 2, various elements of the rubber-coated cord reinforcing layer disposed on the outer peripheral surface side of the carcass layer of the pneumatic stable tire were prepared, and the run-flat durability of the obtained tire was measured. . Table 2 shows the results.

The fiber cord used for the rubber-coated cord in Table 2 is aramid fiber (thickness 1670 dTex ×
2), polyester fiber (1670dTex × 2)
Book).

[0027]

[Table 1]

[0028]

[Table 2]

The durability of each of the above-mentioned Examples during normal running (tire internal pressure: 3.0 (Kgf / cm ² )) was evaluated.

As shown in Table 2, it can be seen that the pneumatic stable tire of the present invention is excellent in run flat durability while maintaining durability at the time of filling with internal pressure.

When a cord made of polyester was used as the cord of the rubber-coated cord reinforcing layer (Comparative Example 1), a case where the rubber-coated cord reinforcing layer was not used (Comparative Example 2), and a polyester fiber was used as the cord of the carcass layer. In this case (Comparative Examples 3 and 4), the run flat durability deteriorates.
In addition, in comparison between Example 2 and Comparative Examples 1 and 3, it is understood that the pneumatic safety tire of the present invention exhibits an excellent effect only when the two conditions are satisfied.

[0032]

As described above, in the pneumatic safety tire of the present invention, the rubber-coated cord reinforcing layer using aramid fiber is disposed near the carcass layer, and the aliphatic polyamide-based fiber is used as the carcass layer cord. Thereby, there is an excellent effect that the durability at the time of internal pressure filling is maintained, and the lightness and the run flat durability are improved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a pneumatic safety tire according to the present invention in which a rubber-coated cord reinforcing layer is provided along the outer peripheral surface of a carcass.

FIG. 2 is a schematic cross-sectional view of a pneumatic safety tire according to the present invention in which a rubber-coated cord reinforcing layer is provided between a carcass and a reinforcing rubber layer.

[Sign]

 DESCRIPTION OF SYMBOLS 10 Pneumatic safety tire 12 Bead ring 14 Bead filler 16 Side wall 18 Carcass layer 20 Belt layer 22 Tread part 24 Reinforcement rubber layer 26 Rubber coating cord reinforcement layer

Claims (2)

[Claims] 1. A side wall having a bead ring buried at a tip portion thereof extends from both ends of a cylindrical crown portion toward a radially inner side, and a gap extending from one of the sidewalls to the other sidewall through the crown portion. A carcass layer made of at least one fiber cord radial ply and having both ends rolled up and wound axially outward around a bead ring, and a plurality of non-extensible belt layers on the outer periphery of a crown portion of the carcass layer; A pneumatic safety tire having a reinforcing rubber layer having a crescent-shaped cross section on the inner peripheral surface of the carcass layer of the side wall while reinforcing the tread portions sequentially. Using a reinforcing cord made of a system fiber, and rubber coated on the sidewall portion,
A pneumatic safety tire comprising at least one rubber-coated cord reinforcing layer composed of a twisted cord made of aramid fiber. 2. The pneumatic safety tire according to claim 1, wherein the aliphatic polyamide fiber is 46 nylon.